Editor's note: This was originally published by ESPN Argentina. Read it here.

MOSCOW -- Argentina's 1-1 draw against Iceland in their World Cup opener left them with at least three certainties: They can (and need to) play much better; doubts persist regarding key positions; and "this is just the beginning," the phrase that has become the motto of both players and coach alike.

While the tie at Spartak Stadium is not a complete disaster, it confirmed that Argentina's group is not as simple as it was initially believed, and in a World Cup, any margin of error is awfully narrow. Jorge Sampaoli knows this, and so it wouldn't be a surprise if he decides to tinker with his lineup for Thursday's match against Croatia, a vital game if they are to extend their stay in Russia beyond the group stage.

Line by line, these are the replacements Sampaoli is considering, with three of them falling under the category of "very probable."

Who will be in goal?

Had Sergio Romero been fit, there wouldn't be so much speculation as to the starting goalkeeper. Given his injury absence, Willy Caballero, Franco Armani and Nahuel Guzman have been locked in a very tight competition for the No. 1 job, particularly the first two. Caballero didn't really inspire confidence in the opening match, but in his defense, the back line is completely new. Could he lose his starting role to River Plate's No. 1 moving forward? It's hard to believe that this would happen right now.

Fixing the defense

It's very likely that Sampaoli decides to go with Gabriel Mercado at right-back, as he is a more rigorous marker than Eduardo Salvio, an attack-minded gamble that didn't work out against Iceland. At center-back, Marcos Rojo wasn't up to the level he showed at the last World Cup but should continue to partner up with Nicolas Otamendi -- especially as they'll have to control a striker as tough as Mario Mandzukic.

The leading candidate to replace him, Federico Fazio, has fallen in the coach's estimation. Against an opponent like Croatia, expect Sampaoli to stick with a back four and not gamble with a three-man line.

Jorge Sampaoli has some big decisions to make ahead of Argentina's next game, particularly in terms of defense and midfield. AP Photo/Andre Penner

Getting more play from the midfield

The main criticism toward Sampaoli focused on the lack of creativity as a result of starting Javier Mascherano and Lucas Biglia together. The pair weren't functional to the needs of the team against Iceland, and the Milan central midfielder was replaced by Ever Banega later on.

What could happen in the second game? Giovani Lo Celso of Paris Saint-Germain has a good chance to take the place of either Biglia or Mascherano (more likely the former) and be the link between defense and attack. The former Rosario Central player started the final five friendlies and was tested in the lead-up to the World Cup, so much so that it was surprising he didn't play in the first game. Lo Celso could also play a defensive role against Ivan Rakitic or Luka Modric. Enzo Perez could also be an option, albeit a less likely one.

Time to turn to Pavon

Every time he gets in, Cristian Pavon turns a profit. Boca's forward reaches the back easily from both lines and has gotten along with Lionel Messi from the beginning. Angel Di Maria, a starter under Sampaoli (except against Spain), showed little in his first outing and is likely to lose his place on the left. Maximiliano Meza delivered in his first World Cup exhibition and should play the next game on the right.

Aguero deserves to continue

Man City forward Sergio Aguero arrived in Russia as the No. 9 for this team, and his goal against Iceland confirmed his position. If he's in his best form, there's no reason to replace him. Gonzalo Higuain, an animal against zonal defending, is still lying in wait for his chance. Sadly, Paulo Dybala does not look like an option, at least with this system.

The prospect of trying out a different scheme was a missed opportunity in the opening match. It's likely that Sampaoli chose that formula given the importance of the first game no matter the opponent. Against Croatia, it's almost a certainty he will go for a 4-2-3-1 with some personnel changes.

Will there be any surprises? Beyond the shadow of a doubt. It is a World Cup, and in Sampaoli's world, changes are always on the agenda.